Over-Speed Indicator
This
circuit is designed for indicating over-speed and direction of rotation
of the motor used in mini hand tools, water pump motors, toys and other
appliances.
A 12V DC motor (M1) is coupled to the rotating part of the appliance with a suitable fixing arrangement. When the motor rotates, it develops a voltage.
This over-speed indicator is built around operational amplifier CA3140 (IC1). Set the reference voltage (depending on the desired speed) by adjusting preset VR1 at pin 2 of IC1. When the voltage developed at pin 3 of IC1 is higher than the reference voltage at pin 2, output pin 6 of comparator IC1 goes high to sound piezobuzzer PZ1 and light up LED3.
The
rotation indicator circuit is built around AND gate 74LS08 (IC2). Pin 2
of gate N1 goes high when the motor rotates in forward direction, while
pin 1 of gate N1 is pulled high via resistor R2. When both pins 1 and 2
are high, output pin 3 of gate N1 goes high to light up LED1.
Similarly, pin 5 of gate N2 goes high when the motor rotates in reverse
direction. When both pins 4 and 5 are high, output pin 6 of gate N2 goes
high to light up LED2.
A 12V DC motor (M1) is coupled to the rotating part of the appliance with a suitable fixing arrangement. When the motor rotates, it develops a voltage.
This over-speed indicator is built around operational amplifier CA3140 (IC1). Set the reference voltage (depending on the desired speed) by adjusting preset VR1 at pin 2 of IC1. When the voltage developed at pin 3 of IC1 is higher than the reference voltage at pin 2, output pin 6 of comparator IC1 goes high to sound piezobuzzer PZ1 and light up LED3.
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bt this ckt is nt working. why we have connect zener and d2 and d1 to grd? plz reply soon
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